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systemd/units/systemd-resolved.service.m4.in

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2014-05-16 22:14:23 +04:00
# This file is part of systemd.
#
# systemd is free software; you can redistribute it and/or modify it
# under the terms of the GNU Lesser General Public License as published by
# the Free Software Foundation; either version 2.1 of the License, or
# (at your option) any later version.
[Unit]
Description=Network Name Resolution
Documentation=man:systemd-resolved.service(8)
Documentation=http://www.freedesktop.org/wiki/Software/systemd/resolved
Documentation=http://www.freedesktop.org/wiki/Software/systemd/writing-network-configuration-managers
Documentation=http://www.freedesktop.org/wiki/Software/systemd/writing-resolver-clients
After=systemd-networkd.service network.target
# On kdbus systems we pull in the busname explicitly, because it
# carries policy that allows the daemon to acquire its name.
Wants=org.freedesktop.resolve1.busname
After=org.freedesktop.resolve1.busname
[Service]
Type=notify
Restart=always
RestartSec=0
ExecStart=@rootlibexecdir@/systemd-resolved
WatchdogSec=3min
resolved: respond to local resolver requests on 127.0.0.53:53 In order to improve compatibility with local clients that speak DNS directly (and do not use NSS or our bus API) listen locally on 127.0.0.53:53 and process any queries made that way. Note that resolved does not implement a full DNS server on this port, but simply enough to allow normal, local clients to resolve RRs through resolved. Specifically it does not implement queries without the RD bit set (these are requests where recursive lookups are explicitly disabled), and neither queries with DNSSEC DO set in combination with DNSSEC CD (i.e. DNSSEC lookups with validation turned off). It also refuses zone transfers and obsolete RR types. All lookups done this way will be rejected with a clean error code, so that the client side can repeat the query with a reduced feature set. The code will set the DNSSEC AD flag however, depending on whether the data resolved has been validated (or comes from a local, trusted source). Lookups made via this mechanisms are propagated to LLMNR and mDNS as necessary, but this is only partially useful as DNS packets cannot carry IP scope data (i.e. the ifindex), and hence link-local addresses returned cannot be used properly (and given that LLMNR/mDNS are mostly about link-local communication this is quite a limitation). Also, given that DNS tends to use IDNA for non-ASCII names, while LLMNR/mDNS uses UTF-8 lookups cannot be mapped 1:1. In general this should improve compatibility with clients bypassing NSS but it is highly recommended for clients to instead use NSS or our native bus API. This patch also beefs up the DnsStream logic, as it reuses the code for local TCP listening. DnsStream now provides proper reference counting for its objects. In order to avoid feedback loops resolved will no silently ignore 127.0.0.53 specified as DNS server when reading configuration. resolved listens on 127.0.0.53:53 instead of 127.0.0.1:53 in order to leave the latter free for local, external DNS servers or forwarders. This also changes the "etc.conf" tmpfiles snippet to create a symlink from /etc/resolv.conf to /usr/lib/systemd/resolv.conf by default, thus making this stub the default mode of operation if /etc is not populated.
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CapabilityBoundingSet=CAP_SETUID CAP_SETGID CAP_SETPCAP CAP_CHOWN CAP_DAC_OVERRIDE CAP_FOWNER CAP_NET_RAW CAP_NET_BIND_SERVICE
PrivateTmp=yes
PrivateDevices=yes
ProtectSystem=full
ProtectHome=yes
ProtectControlGroups=yes
ProtectKernelTunables=yes
MemoryDenyWriteExecute=yes
RestrictRealtime=yes
RestrictAddressFamilies=AF_UNIX AF_NETLINK AF_INET AF_INET6
SystemCallFilter=~@clock @cpu-emulation @debug @keyring @module @mount @obsolete @raw-io
[Install]
WantedBy=multi-user.target